Every month, a couple of extra cryptocurrency coins go into Kevin Baird’s digital wallet. He doesn’t cash them out into dollars very often, but when he does, he usually buys a new piece of tech — after all, he’s a computer programmer by day and tech-head in his spare time. He earns the money by renting his spare computer space to a network of strangers: He has a couple of Raspberry Pi drives connected to his home Wi-Fi along with his personal computer, all of which is enough to generate a “few extra dollars,” he says, without having to lift a finger.

Those with a computer science degree call it “distributed computing” — translation: Airbnb for computers — an idea that has roots in unpaid systems. Five million computers, for example, are linked up to the University of California, Berkeley’s SETI@home project, which uses volunteers’ computer power to search astronomical data for evidence of alien life. For commercial applications, the big idea is that, whether it’s data storage or processing power, most computing currently occurs in racks of servers in huge data centers. But most of the world’s two billion personal computers aren’t maxed out, leaving as much as one trillion gigabytes of computer space sitting idle (the entirety of Google is estimated to be 10 to 15 billion gigabytes). And, as Uber drivers or Airbnb hosts will tell you, crowd-based networks can mean a nice side income for people with cars or spare rooms — or spare space on their hard drives.

A number of companies are working to make this digital daydream a reality. Baird is one of about 10,000 people who rent their surplus gigabytes to the distributed platform Storj, which launched out of beta testing last month. The prerelease cryptocurrency behind MaidSafe, a data and communications network that’s still in alpha testing, is the tenth most traded in the world. Poland-based Golem intends to build a “worldwide supercomputer” of distributed processing power, a much tougher problem to crack than storage, says its CEO, Julian Zawistowski, though he hopes to launch the first iteration of the product this year. Others already are receiving monthly direct deposits into their PayPal accounts from a system called Gomez Peer, which runs a background program on users’ machines to test website performance. Some of the startups seem a tad sketchy, not surprising when most use the dark-web-style technology of blockchain, the underlying technology behind Bitcoin. That said, the concept “is definitely something that can become viable in the near future,” says Professor Abhishek Chandra, a distributed computing expert at the University of Minnesota, Twin Cities.

The techies at the forefront of the movement dream about changing the entire infrastructure of the internet. Though it may seem as though cloud storage and computing are free, instantaneous and secure, “you pay with your privacy” when using internet services provided by Google, Facebook and others, says MaidSafe COO Nick Lambert, and developers needing wholesale levels of storage have to cough up quite the sum. Plus, the internet’s graduation from the mainframe to the cloud was deceptive, says Storj CEO Shawn Wilkinson, who notes that “the cloud is just another mainframe somewhere else!” Centralized computing also is at risk of hacking, government surveillance and calamitous outages — in February, an Amazon Web Services outage brought down thousands of sites for four hours. Replacing the digital infrastructure with a distributed network could solve these problems and, by leveraging local spare capacity, Chandra says, it even could speed things up. It can currently be more efficient to ship extremely large files on a USB stick via FedEx to Amazon’s data centers than it is to upload them.

But for mere mortals like you and me, the most noticeable change that distributed computing could bring is a handy way to monetize our idling asset. So, how much are we talking about? The network pioneers all give the predictable “it depends” answer — in this case, on minute-by-minute factors of supply and demand. Storj shells out about $5 per month to each provider, though you can earn a bit more if you have a “node” with better internet speeds that’s accessible 24/7. So, it’s not life-changing wealth, but “it’s very passive income,” says Wilkinson. “You’re just downloading a program, hitting go, and you’re earning money.”

In almost all circumstances, it should certainly be enough to cover the cost of your slightly increased electricity and internet bills, but again, “it depends,” sings the chorus of tentative techies. With the exception of Gomez Peer, you’re usually earning some kind of cryptocurrency, which often fluctuates in value, and conversion fees that turn your earnings into spendable cash might render the side hustle revenue-neutral. But as blockchain-based technologies become an increasingly important part of our digital economy, so too the value of our computing power may rise.

Not everyone will sign up for renting a computer to strangers — who knows what could be installed or run on your machine? “All data on the network is broken into chunks and encrypted,” MaidSafe’s Lambert says, trying to reassure. While user Baird has no concerns, thanks to his own understanding of the technology, overcoming the trust gap with the general public is a different challenge. Indeed, the establishment of “digital trust” in platforms like Airbnb and Uber, allowing customers to feel comfortable sleeping in a stranger’s bed or getting into a stranger’s car, is what allowed these types of companies to take off in recent years, says sharing economy expert Arun Sundararajan. In the meantime, Baird is participating more out of technical curiosity than to earn a ton of cash, so he’s not quitting his job any time soon. At $5 a month, that’s probably a good call.